work measurement

1. WORK MEASUREMENT
• Work measurement is concerned with determining the length of time
it should take to complete the job
• Job times are vital inputs for capacity planning, workforce planning,
estimating labor costs, scheduling, budgeting, and designing incentive
systems. From the workers’ standpoint, time standards reflect the
amount of time it should take to do a given job working under typical
conditions.
• Standard time is the time it should take a fully trained and qualified
worker to complete a specific task, working at an efficient, yet
sustainable pace, using specific methods, tools and equipment, raw
materials, and workplace arrangement.

2. Method for work measurement
Stopwatch time study
Standard elemental data
Predetermined data
Work Sampling

3. Stopwatch time study
• Stopwatch time study : development of a time standard based on
observations of one worker taken over a number of cycles.
Appropriate for short, repetitive tasks
• The basic step in time study are :
(1) Define the task to be studied, and inform the worker who will be
studied.
(2) Determine the number of cycles to observe.
(3) Time the job, and rate the worker’s performance.
(4) Compute the standard time

4. Stopwatch time study (Con’t)
The number of cycles that must be timed:
1. The variability of observed times
2. The desired accuracy (percentage or amount)
3. The desired level of confidence for the estimated job time

5. Stopwatch time study (Con’t)
• Number of cycle to be observed (sample size)
• When the desired accuracy is a percent
• When the desired accuracy is a time

7. Stopwatch time study (Con’t)
• Observe time is simply the average of the recorded times

8. Stopwatch time study (Con’t)
• Normal time is the observed time adjusted for worker performance
If ratings are made on an element-by-element basis

9. Stopwatch time study (Con’t)
• Standard time for a job • Allowance job based on the job
time
• Allowances are based on
percentage of time worked
(workday)

11. Standard elemental times
• Standard elemental times derived from a firm’s historical time data.
• The procedure for using standard elemental times consists of the following
steps :
(1)Analyze the job to identify the standard elements
(2)Check the file for elements that have historical times, and record them. Use
time study to obtain others, if necessary
(3)Modify the times if necessary
(4)Sum the elemental times to obtain the normal time, and factor in allowances
to obtain the standard time
• Advantages : the potential savings in cost and effort created by not having to
conduct a complete time study for each job, less disruption of work,
performance ratings do not have to be done; they are generally averaged in the
file times
• Disadvantages : times may not exist for enough standard elements to make it
worthwhile, and the file times may be biased or inaccurate.

12. Predetermined time standards
• Predetermined time standards involve the use of published data based on
extensive research to determine standard elemental times
• Commonly used system is methods-time measurement (MTM) based on
extensive research of basic elemental motions and times. The analyst must
divide the job into its basic elements (reach, move, turn, disengage),
measure the distances involved (if applicable), rate the difficulty of the
element, and then refer to the appropriate table of data to obtain the time
for that element. The standard time for the job is obtained by adding the
times for all of the basic elements.
• Advantages are the following:
1. They are based on large numbers of workers under controlled conditions.
2. The analyst is not required to rate performance in developing the
standard.
3. There is no disruption of the operation.
4. Standards can be established even before a job is done.

13. Work Sampling
• Work sampling is a technique for estimating the proportion of time
that a worker or machine spends on various activities and the idle
time.
• The primary uses are in
(1) ratio-delay studies, which concern the percentage of a worker’s
time that involves unavoidable delays or the proportion of time a
machine is idle, and
(2) analysis of nonrepetitive jobs
• The goal of work sampling is to obtain an estimate that provides a
specified confidence of not differing from the true value by more than
a specified error

15. Work Sampling (con’t)
• Determining the sample size is only one part of work sampling.
The overall procedure consists of the following steps:
1. Clearly identify the worker(s) or machine(s) to be studied.
2. Notify the workers and supervisors of the purpose of the study to avoid
arousing suspicions.
3. Compute an initial estimate of sample size using a preliminary estimate
of p, if available (e.g., from analyst experience or past data). Otherwise,
use pˆ = .50.
4. Develop a random observation schedule.
5. Begin taking observations. Recompute the required sample size several
times during the study.
6. Determine the estimated proportion of time spent on the specified
activity.

16. Random number table
• Table consisting of unordered sequences of numbers, used to
determine random observation schedules.
• Use of these tables enables the analyst to incorporate randomness
into the observation schedule.